Nearly every day some new scientific evidence is published and one of the principal players in the US, the CDC, US Centers for Disease Control and Prevention, updated guidance on its website on Friday to say that coronavirus can commonly spread "through respiratory droplets or small particles, such as those in aerosols", which are produced even when a person breathes, warning that the principal form of propagation of the virus is through the air.
Previously, the CDC had suggested maintaining a physical distance of six feet, disinfecting surfaces, regularly washing hands, and using masks as ways to curb the spread of the virus and prevent one from getting infected. "Once this process has been completed, the update language will be posted", the agency said. For those who know they've come into recent close contact with someone who has a documented infection from the coronavirus SARS-CoV-2 - close contact meaning spending at least 15 minutes 1.83 m or closer to the person - the CDC now simply states: "You need a test".
They also updated the guidance that particles can remain in the air longer and travel farther than originally thought.
The apex global public health agency received and open letter by over 200 scientists outlining evidence that showed floating virus particles can infect people who breathe them in.
The "draft" changes included stating COVID-19 transmits through the air and warned about poorly ventilated situations, saying that is "thought to be the main way the virus spreads". "In general, indoor environments without good ventilation increase this risk", the CDC stated on Friday in a post that has since been taken down.
On August 24, the CDC changed Covid-19 testing guidelines on its website, no longer recommending testing for most people without symptoms.
CNN reported last week that US Health and Human Services communications officials appointed by President Trump had recently pushed to change language of weekly science reports released by the CDC so as not to undermine Trump's political message, according to a federal health official.
"We have been saying "wear a mask" and "6 feet apart" for months", tweeted Abraar Karan, a physician at Brigham and Women's Hospital in Boston and Harvard Medical School.
"Evidence has been accumulating for some time. And 6 feet apart may be insufficient, [especially] indoors [with] poor ventilation". Masks should not replace other prevention measures.
The CDC also added new measures to its information about protecting yourself and others. According to the agency, people who have likely been exposed to an infected person do not necessarily need to get tested for.